The invention presented here relates to new pentaerythritol derivatives, their preparation and use and intermediates for synthesis of the same, which are used in particular as pharmaceutical products.
Organic nitrates such as glycerol trinitrate (GTN) (Murrel, Lancet: 80, 113, 151 (1879)), pentaerythrityl tetranitrate (PETN) (Risemann et al., Circulation, Vol. XVII, 22 (1958), U.S. Pat. No. 2,370,437), isosorbitol-5-mononitrate (ISMN) (DE-OS-22 21 080, DE-OS-27 51 934, DE-OS-30 28 873, DE-PS-29 03 927, DE-OS-31 02 947, DE-OS-31 24 410, EP-A1-045 076, EP-A1-057 847, EP-A1-059 664, EP-A1-064 194, EP-A1-067 964, EP-A1-143 507, U.S. Pat. Nos. 3,886,186, 4,065,488, 4,417,065, 4,431,829), isosorbitol dinitrate (ISDN) (L. Goldberg, Acta Physiolog. Scand. 15, 173 (1948)), propatyl nitrate (Mxc3xa9dard, Mem. Poudres 35: 113 (1953)), trolnitrate (FR-PS-984 523) or nicorandil (U.S. Pat. No. 4,200,640) and similar compounds are vasodilators, some of which have been used for many decades for the selective treatment of angina pectoris and ischaemic heart disease (IHK) with a very wide therapeutic application (Nitrangin(copyright), Pentalong(copyright), Monolong(copyright), etc.). Other pentaerythrityl nitrates and their preparation have also been described (Simecek, Coll. Czech. Chem. Comm. 27 (1962), 363; Camp et al., J. Am. Chem. Soc. 77 (1955), 751). Organic nitrates of a more recent type such as for example SPM 3672 the ethyl ester of (N-[3-nitratopivaloyl]-L-cysteine) (U.S. Pat. No. 5,284,872) and its derivatives are intended to have comparable and improved pharmacological efficacy when used in the areas mentioned above. Furthermore, the preparation of 3-nitryloxy-2,2-bis-(nitryloxymethyl)propionic acid and its methyl ester (Nec. Chem. Prum. (1978), 28 (2), 84) has also been disclosed. The galenic processing of organic nitrates to give pharmaceutical preparations for the treatment of angina pectoris or ischaemic heart disease is generally well recognised. It is performed using methods of operation and rules which are generally familiar to a person skilled in the pharmaceutical field, wherein the choice of technologies to be used and the galenic auxiliary agents to be used are governed in the first instance by the active substance to be processed. In this case questions relating to its chemico-physical properties, in particular the explosive properties which are known to be associated with organic nitrates, which requires the use of special safety precautions and special processing technologies, the form of application chosen, the period of activity required and the avoidance of medicament/auxiliary agent incompatibilities are of particular importance. When using medicaments for angina pectoris or ischaemic heart disease, peroral, parenteral, sublingual or transdermal application in the form of tablets, dragees, capsules, solutions, sprays or patches has been described in particular (DD-A5-293 492, DE-AS-26 23 800, DE-OS-33 25 652, DE-OS-33 28 094, DE-PS-40 07 705, DE-OS-40 38 203, JP application 59/10513 (1982)). In addition to use as a nitrosing substance which has been disclosed for many years, their use for the treatment and prevention of illnesses which are caused by pathologically elevated concentrations of sulfur-containing amino acids in the body fluids has also been described. These conditions, caused by congenital or acquired defects in the metabolism of these amino acids and which are characterised by elevated blood and urine concentrations of said amino acids (homocystinurea), are combined under the expression homocystinanaemia (WO-A1-92/18002). The use of specific organic nitrates as endothelial protective agents (DE-A1-44 10 997) and as agents for the treatment of erectile disfunction (WO-A1-96/32118) has been described recently. Furthermore, it is known that 3-amino-1,2,4-oxadiazol-5-ones are suitable as proactive drugs for hydroxyguanidines (Rehse et al. Arch. Pharm. Pharm. Med. Chem. 329, 535 (1996)). On the one hand, the currently disclosed organic nitrates (esters of nitric acid) are associated with a number of therapeutic disadvantages. Thus, for instance, so-called nitrate tolerance is observed; i.e. the decrease in the effect of nitrate at high dosage or when administering nitrates with a long-term effect. Side effects such as headaches, nausea, dizziness, feeling weak, reddening of the skin and the risk of a large drop in blood pressure with reflectorial tachycardia have also been demonstrated (Mutschler, Arzneimittelwirkungen, Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart, 1991). On the other hand, PETN has a number of outstanding properties as an active substance which is the reason for the preferred use of this compound as a pharmaceutical product as compared with other organic nitrates, wherein however restricted bioavailability of this active substance has been observed (set of monographs xe2x80x9cPentaerythrityltetranitratxe2x80x9d Dr. Dietrich Steinkopff Verlag, Darmstadt, 1994 to 1995). Lipophilic organic nitrates are generally active for only a short time due to a relatively rapid metabolic degradation to give less active or inactive biotransformation products (Bonn, xe2x80x9cPharmakokinetik organischer Nitratexe2x80x9d in xe2x80x9cPentaerythrityltetranitratxe2x80x9d, Dr. Dietrich Steinkopff Verlag, Darmstadt, 1995).
The object of the invention is to provide new compounds derived from pentaerythritol with pharmacologically advantageous effects.
The object of the invention is achieved by the new compounds of the formulae (I) and (III)
(O2NOCH2)mC(CH2OH)n(CH2COR1)o(COR1)pxe2x80x83xe2x80x83(I)
(O2NOCH2)mC(CH2OH)n(CH2COR3)o(COR3)pxe2x80x83xe2x80x83(III)
wherein R1 represents a group of the formula (II), 
and R3 represents a group of the formula (IV) 
R2 represents a C1 to C20 alkyl group, in particular methyl, ethyl, n-propyl, i-propyl, n-butyl, n-pentyl, n-hexyl, n-octyl, benzyl, cyclohexylmethyl, 4-chlorobenzyl, 4-nitrobenzyl, 2-phenylethyl, 3-phenylpropyl, 3-cyclohexylpropyl, 3-phthalimidylpropyl, 1-naphthylmethyl, cinnamyl, 5-ethoxycarbonylbutyl, 3-aminopropyl, xe2x80x94(CH2)3CH(NHCOCH3)COOH, xe2x80x94(CH2)3CH(NHCOCH3)COOCH3, or 1,6-hexane-bis and m to p are integers, for which the following is true: m+n+o+p=4, mxe2x89xa71 and o and/or pxe2x89xa71. Compounds in which R2 represents n-butyl, n-pentyl, n-hexyl, benzyl, 2-phenylether, 3-phenylpropyl, 3-phthalimidylpropyl or 5-ethyoxycarbonylbutyl are preferred.
The starting compounds for synthesising compounds of the formulae (I) and (III) are pentaerythritol or its nitrates, i.e. pentaerythrityl mononitrate (PEMN), pentaerythrityl dinitrate (PEDN), pentaerythyrityl trinitrate (PETriN) and pentaerythrityl tetranitrate (PETN), which are synthetically available in good yields in a manner known per se (Simecek, Coll. Czech. Chem. Comm. 27 (1962), 363; Camp et al., J. Am. Chem. Soc. 77 (1955), 751). The compounds PEMN, PEDN and PETriN are converted into the corresponding tri-, di- or monocarboxylic acids by complete or partial oxidation of any hydroxymethyl groups present, and the corresponding derivatives with nitroxy, hydroxyl and carboxyl functions are optionally obtained from these by partial hydrazinolysis of the corresponding nitrate function. The formation of compounds of the formulae (I) and (III) is performed by methods of synthesis and procedures which are familiar to a person skilled in the art, for example by known ester or amide-forming reactions. Compounds of the formula (IV.1), (FIG. 1), are used as starting materials which are also required and the synthesis of these is described in Rehse et al; Arch. Pharm. Pharm. Med. Chem 329, 535 (1996), wherein reference is now made to the disclosures in this publication, and in which in addition one or two hydrogen atoms in the amino group may be replaced by a suitable leaving group, and also compounds of the formula (V), 
in which R2 is defined in the same way as for formula (I) and R4 represents H or a suitable leaving group, which are obtainable in good yield from compounds of the formula (IV.1) via the reaction scheme shown in FIG. 1. 
Compounds of the formula (V) 
in which R2 is defined in the same way as given for formula (I) and R4 represents H, a C1 to C6 alkanoyl group, salicyloyl or acetylsalicyloyl, are independent embodiments of the invention. Compounds in which R2 represents n-butyl, n-pentyl, n-hexyl, benzyl, 2-phenylethyl, 3-phenylpropyl, 3-phthalimidylpropyl or 5-ethoxycarbonylbutyl are preferred. Furthermore, compounds in which R4 represents salicyloyl or acetylsalicyloyl and compounds in which R2 represents n-butyl, n-pentyl, n-hexyl, benzyl, 2-phenylethyl, 3-phenylpropyl, 3-phthalimidylpropyl or 5-ethoxycarbonylbutyl and R4 represents salicyloyl or acetylsalicyloyl are also preferred.
Compounds of the formula (VI) may also be used to achieve the object of the invention,
(O2NOCH2)mC(CH2OH)n(CH2COR5)o(COR5)pxe2x80x83xe2x80x83(VI)
in which R5 is (2-carboxyphenyl)oxy or (2-alkoxycarbonylphenyl)oxy and m to p are integers, and: m+n+o+p=4, mxe2x89xa71 and o and/or pxe2x89xa71, furthermore compounds of the formula (VII),
(HOCH2)q(O2NOCH2)rC(CH2OR6)sxe2x80x83xe2x80x83(VII)
in which R6 is salicyloyl or acetylsalicyloyl and q to s are integers, and:
q+r+s=4and r and s are xe2x89xa71,
furthermore compounds of the formula (VIII),
(O2NOCH2)mC(CH2OH)n(CH2COR7)o(COR7)pxe2x80x83xe2x80x83(VIII)
in which R7 is a group of the formula (IX) 
R8 and R9, independently, represent a C1 to C6 alkyl group or together represent a C1 to C6 alkylene group, R10 represents OH, NHR8R9, C1 to C6 alkoxy, (2-carboxyphenyl)oxy, (2-alkoxycarbonylphenyl)oxy, (1-carboxymethyl-2-dialkylamino)ethoxy, (1-carboxymethyl-2-trialkylammonium)ethoxy, (1-alkoxycarbonylmethyl-2-dialkylamino)ethoxy, (1-alkoxycarbonylmethyl-2-trialkylammonium)ethoxy, and m to p are integers, and:
m+n+o+p=4,mxe2x89xa71 and o and/or pxe2x89xa71.
A particular embodiment of the present invention is compounds of the formula (X), 
in which R8 to R10 are defined in the same way as for formula (IX) and R11 represents NO2, and compounds of the formula (XI) derived therefrom 
in which R12 also represents a C1 to C6 alkyl, in particular methyl, ethyl or n-propyl group, and X represents a group capable of forming an anion, which does not have to be present if the group COR10 has the ability to form internal salts. Compounds of the formula (XII) 
of the formula (XIII), 
and of the formula (XIV), 
in which R13 represents H or a C1 to C6 alkyl group are particularly preferred.
Compounds of the formula (XV) in particular contribute to achieving the object of the invention,
(HOCH2)q(O2NOCH2)rC(CH2OR14)sxe2x80x83xe2x80x83(XV)
in which R14 represents the acyl group from a compound of the formula (X) to (XIV), in which R11 also may represent H, a C1 to C6 alkanoyl group, salicyloyl or acetylsalicyloyl or xe2x80x94COxe2x80x94CH2xe2x80x94CH(OH)xe2x80x94CH2xe2x80x94NR8R9, and q to s are integers, and: q+r+s=4 and r and s are xe2x89xa71, in particular compounds of the formula (XVI), 
and those of the formula (XVII), 
Depending on the conditions of reaction and the starting materials, the end product is obtained either as a free acid or base, as a basic or acid addition salt or a betaine, each of which lie within the scope of the invention. Thus, acidic, basic, neutral or mixed salts and hydrates may be obtained. On the one hand, each of the salts may be converted into the free acid or base by using corresponding agents or by ion-exchange in a manner known per se. On the other hand, the free acids or bases obtained may form salts with organic or inorganic bases or acids. When preparing base addition salts, bases are used in particular which form suitable therapeutically acceptable salts.
These bases are for example hydroxides or hydrides of the alkali and alkaline-earth metals, ammonia and amines. When preparing acid addition salts, those acids are preferably used which form suitable therapeutically acceptable salts. These types of acids are for example, hydrohalic, sulfonic, phosphoric, nitric and perchloric acids, furthermore aliphatic, acyclic, aromatic, heterocyclic carboxylic or sulfonic acids such as formic, acetic, propionic, succinic, glycolic, lactic, malic, tartaric, citric, gluconic, sugar, glucuronic, ascorbic, maleic, hydroxymaleic, pyruvic, phenylacetic, benzoic, p-aminobenzoic, anthranilic, p-hydroxybenzoic, salicylic, acetylsalicylic, p-aminosalicylic, embonic, methanesulfonic, ethanesulfonic, hydroxyethanesulfonic, ethylenesulfonic, halobenzenesulfonic, toluenesulfonic, naphthylsulfonic or sulfanilic acids and amino acids such as for example methionine, tryptophane, lysine or arginine. These and other salts of the new compound (sic) may be used as agents for purifying the free acids or bases which are obtained. Salts of the acids or bases may be produced and isolated from solutions, and then the free acid or base may be recovered from a fresh salt solution in a purer condition. As a result of the relationship between the new compounds in their free form and as their salts, these salts also lie within the scope of the invention. Some of the new compounds may be present as optical isomers or racemates, depending on the choice of starting materials and the method used, or if they contain at least two asymmetric carbon atoms they may also be present as an isomeric mixture (racemate mixture). The isomeric mixture obtained (racemate mixture) may be separated into pure racemates with the assistance of chromatography or fractional crystallisation to give two stereoisomers (diastereomers). The racemates obtained may be separated using methods known per se, such as by recrystallising from an optically active solvent, by using microorganisms, by reacting with optically active agents to produce compounds which can be separated or by separating on the basis of the different solubilities of the diastereoisomers. Suitable optically active agents are the L- and D-forms of tartaric, di-o-toluyltartaric, malic, mandelic, gluconic, sugar, glucuronic, camphorsulfonic, quinine or binaphthylphosphoric acids. The more active portion of the two mirror image isomers is preferably isolated. The starting materials are known or, if they are intended to be new, can be obtained by methods known per se. At the same time the use of pharmacologically acceptable derivatives of all the previously mentioned compounds is possible. In particular, useful addition compounds, salts or enzymatically or hydrolytically decomposable compounds such as esters, amides, hydrazides, which are obtained e.g. by N-amination (DD-B1-230 865 and DD-A3-240 818) of the corresponding amino compounds, hydrazinium salts and similar represent, if not mentioned above, possible variations.
Compounds according to the invention may be used clinically as such or as part of a pharmaceutical preparation, as an individual active substance in combination with each other or with known heart/circulation or vascular treatments, for example combined with ACE inhibitors, antiarteriosclerotic agents, antihypertensive agents, beta-blockers, cholesterol reducers, diuretics, calcium antagonists, coronary dilators, lipid reducers, peripheral vasodilators, phosphodiesterases, in particular xe2x80x94(V)xe2x80x94, or thrombocyte aggregation inhibitors or other substances also used as treatment for heart/circulation conditions. The provision of pharmaceutical preparations is performed using methods and rules which are generally familiar to a person skilled in the pharmaceutical field wherein the choice of technology to be used and the galenic auxiliary agents to be used are governed in the first instance by the active substance being processed. Here matters relating to its chemico-physical properties, the form of application selected, the duration of activity required, the location of action and avoidance of medicament/auxiliary substance incompatibilities are of particular importance. The person skilled in the art therefore has to select the form of medicament, the auxiliary agents and the method of preparation using known substance and process parameters in a manner which is trivial per se. The relevant form of medicament should be designed in such a way that it contains the particular active substance in an amount which produces therapeutic levels in the plasma and enables the daily dose to be divided into one to two units for controlled release systems and into up to ten individual doses in other types of medicament. Continuous application using long term infusion is also suitable. To produce endothelial protective effects, long lasting therapeutic levels in the blood are generally striven for. According to the invention the compounds mentioned may be applied in particular orally, intravenously, parenterally, sublingually or transdermally. The particular medicament preparation is preferably provided in liquid or solid form. Solutions, in particular for the preparation of drops, injections or aerosol sprays, furthermore suspensions, emulsions, syrups, tablets, film-coated tablets, dragees, capsules, pellets, powders, pastilles, implants, suppositories, creams, gels, salves, patches or other transdermal systems are suitable for this purpose. The pharmaceutical preparations contain conventional galenic organic or inorganic supports and auxiliary substances which should themselves be chemically inert towards the particular active substances. Chemical derivatisation during application to support materials is also included. This applies in particular to the production of adducts with sugar derivatives such as croscarmeloses or cyclodextrins. Suitable pharmaceutical auxiliary substances are, without being restricted thereto, water, salt solutions, alcohols, plant oils, polyethylene glycols, gelatines, lactoses, amyloses, magnesium stearate, talcum, highly dispersed silicon dioxide, paraffin, fatty acid mono- and diglycerides, cellulose derivatives, polyvinylpyrrolidone and the like. The preparation may be sterilised and if required may have added thereto auxiliary substances such as fillers, binders, lubricants, mould release agents, intestinal lubricants, decomposing agents, moisture retainers, adsorption agents or antidisintegrants, preservatives, stabilisers, emulsifiers, solvent promoters, salt to alter the osmotic pressure, buffer solutions, dyes, fragrances, flavourings or sweeteners. A person skilled in the pharmaceutical art is able to avoid medicament/auxiliary agent incompatibilities by basing his choice on the relevant substance parameters.
Surprisingly, it was found that compounds according to the invention have the required properties. In addition they are characterised by an optimised NO liberation, e.g. due to their differentiated concentration of reductive biotransforming NO precursor groups or an improved multi-phase NO liberation and, depending on the ultimate application, increased lipophilicity or hydrophilicity and also by lowering the pharmacodynamic threshold, reduced endothelial increase in the plasma, pronounced thrombocyte aggregation inhibition by thrombocyte-active groups and, even in sub-haemodynamic dosage, by endothelial-protective effects. Particularly advantageous is the fact that compounds according to the invention are characterised by good penetration of physiological membranes. Furthermore it was found that in particular the compounds derived from carboxyl compounds and their salts or quaternary ammonium compounds can be processed to give pharmaceutical preparations in the form of sprays and injection solutions. Compounds used in accordance with the invention, surprisingly, show in functional tests on isolated blood vessels (rabbit aorta) a high vaso-dilatory property with improved bioavailability and increased hydrophilicity as well as facilitated biotransformation to give the final metabolites, wherein these final metabolites are generally very well tolerated or are compounds which are normally present in the body. They are characterised, surprisingly, as strongly hydrophilic, nitrate vasodilators which have a long half-life and improved bioavailability as compared with lipophilic nitrates. It was surprising that compounds according to the invention could on the one hand trigger the strong pharmacodynamic effects which are typical of lipophilic organic nitrates without their pronounced short term effect and on the other hand have the characteristic long term effect of more hydrophilic organic nitrates, that is they combine the advantages of lipophilic and hydrophilic organic nitrates within the compounds used without exhibiting any of their pharmacodynamic disadvantages. Thus using the invention described, improved and considerably extended therapeutic opportunities are opened up and pathological conditions such as heart and circulatory illnesses, in particular coronary heart disease, vascular stenoses and bleeding problems in the peripheral arteries, hypertonia, micro and macroangiopathies within the context of diabetes mellitus, arteriosclerosis and the secondary illnesses resulting therefrom, furthermore erectile disfunction, elevated internal eye pressure, uterine spasms, menopausal problems, etc. can be treated. Some of the compounds described above may be characterised, on the basis of their chemico-physical properties, as explosives, which may also enable their use as such. A person skilled in the art is able to select compounds for this purpose on the basis of known test processes. In contrast to that, however, a number of substances according to the invention do not have this property or this property is only weakly expressed so that these compounds are characterised by the absence of the disintegrant properties which are typical of organic nitrates while at the same time being characterised by the retention of and improvement in pharmacological effects due to a particularly simple and reliable method of preparation, handling and further processing. In addition compounds described in the present invention are useful starting compounds and intermediates for the preparation of chemical derivatives which may themselves be used as pharmaceutical active substances. The examples given below are intended to explain the invention in more detail without however restricting its scope.